ML022390175
| ML022390175 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 09/27/2002 |
| From: | Dick G NRC/NRR/DLPM/LPD3 |
| To: | Skolds J Exelon Generation Co |
| References | |
| TAC MB5237, TAC MB5238, TAC MB5239, TAC MB5240 | |
| Download: ML022390175 (5) | |
Text
September 27, 2002 Mr. John L. Skolds, President Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
HOT LEG SWITCHOVER CONFIRMATORY ANALYSIS - BRAIDWOOD STATION, UNITS 1 AND 2, AND BYRON STATION, UNITS 1 AND 2 (TAC NOS. MB5237, MB5238, MB5239, AND MB5240)
Dear Mr. Skolds:
By letter dated April 12, 2002, Exelon Generation Company, LLC (Exelon) submitted its hot leg switchover confirmatory analysis in accordance with the license condition imposed on Braidwood Station, Units 1 and 2 (Braidwood), and Byron Station, Units 1 and 2 (Byron) in license amendments 113 and 119 respectively. The license conditions required submittal of the analysis by June 1, 2002.
As a part of the analysis supporting its request for approval of a power uprate for Braidwood and Byron, Exelon calculated the value of 8.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as the maximum allowable time in which operators must direct some emergency core cooling system (ECCS) recirculation flow to the reactor coolant system hot legs (i.e., hot leg switchover [HLSO]) during a loss of coolant accident scenario in order to prevent boron precipitation in the reactor core. In its review of Exelons analysis (section 3.1.3 of the safety evaluation, dated May 4, 2001, supporting license amendments 113 and 119), the NRC staff questioned several of the assumptions used in the formulation of the calculation. The NRC staff concluded that continued operation of the plants was acceptable in the short term but that additional information was required to support the HLSO calculations. Consequently, a license condition was added to the license. The license condition stated, The licensee shall submit to the NRC a confirmatory analysis using a model acceptable to the NRC justifying the value of 8.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> for the time of switchover to hot leg injection following a loss-of-coolant accident; or recalculate the switchover time using the currently accepted methodology.
There were two assumptions that were in question: (1) Exelon used a decay heat generation rate of 1.0 times the 1971 ANS standard for a finite operating time rather than 1.2 times the standard as required by Section I.A.4 of Appendix K to 10 CFR Part 50 (Appendix K); and (2) Exelons HLSO analysis assumed that the ECCS water subcooling was 170 F. The staff questioned the assumption on the basis that the licensee had only justified that interaction with 33 percent of the steam could be accommodated when assuming a 170 F lower plenum temperature and the decay heat generation rate of 1.0 times the 1971 ANS standard for a finite operating time.
In Exelons letter of April 12, 2002, it reported the results of its reanalysis of the HLSO time using an assumed decay heat generation rate as required in Appendix K and without the assumption of subcooling. Also, Exelon used a boron measurement uncertainty value of 25 ppm rather than the 50 ppm used in previous calculations. The lower uncertainty value was
J. Skolds used on the basis that it is consistent with the Institute for Nuclear Power Operations (INPO) guidelines and that the Exelon chemistry procedures follow the INPO guideline. Exelon also stated that the performance check done for the boron titration equipment at both Byron and Braidwood bounds the 25 ppm uncertainty value. The results of the reanalysis yielded a HLSO time of 6.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
The NRC staff has reviewed the information provided by Exelon in support of its reanalysis of the HLSO time and found it to be acceptable. Further, we have concluded that Exelon has satisfied the license condition related to HLSO time.
Sincerely,
/RA/
George Dick, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-456, STN 50-457, STN 50-454, and STN 50-455 cc: See next page used on the basis that it is consistent with the Institute for Nuclear Power Operations (INPO) guidelines and that the Exelon chemistry procedures follow the INPO guideline. Exelon also stated that the performance check done for the boron titration equipment at both Byron and Braidwood bounds the 25 ppm uncertainty value. The results of the reanalysis yielded a HLSO time of 6.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
The NRC staff has reviewed the information provided by Exelon in support of its reanalysis of the HLSO time and found it to be acceptable. Further, we have concluded that Exelon has satisfied the license condition related to HLSO time.
Sincerely,
/RA/
George Dick, Jr., Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-456, STN 50-457, STN 50-454, and STN 50-455 cc: See next page Distribution:
PUBLIC PD3-2 r/f A. Mendiola C. Rosenberg G. Dick M. Chawla F. Akstulewicz W. Lyon OGC ACRS G. Grant, RIII A. Stone, RIII ADAMS Accession Number: ML022390175
- See previous concurrence OFFICE PM:LPD3-2 PM:LPD3-2 LA:LPD3-2 SC:RTSB*
SC:LPD3-2 NAME GDick MChawla CRosenberg FAkstulewicz AMendiola DATE 09/24/02 09/24/02 09/24/02 09/24/02 09/27/02 OFFICIAL RECORD COPY
Byron/Braidwood Stations cc:
Ms. C. Sue Hauser, Project Manager Westinghouse Electric Corporation Energy Systems Business Unit Post Office Box 355 Pittsburgh, PA 15230 Joseph Gallo Gallo & Ross 1025 Connecticut Ave., NW, Suite 1014 Washington, DC 20036 Howard A. Learner Environmental Law and Policy Center of the Midwest 35 East Wacker Dr., Suite 1300 Chicago, IL 60601-2110 U.S. Nuclear Regulatory Commission Byron Resident Inspectors Office 4448 N. German Church Road Byron, IL 61010-9750 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950 Chairman, Ogle County Board Post Office Box 357 Oregon, IL 61061 Mrs. Phillip B. Johnson 1907 Stratford Lane Rockford, IL 61107 George L. Edgar Morgan, Lewis and Bockius 1800 M Street, NW Washington, DC 20036-5869 Attorney General 500 S. Second Street Springfield, IL 62701 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, IL 62704 Byron Station Manager Exelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794 Site Vice President - Byron Exelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794 U.S. Nuclear Regulatory Commission Braidwood Resident Inspectors Office 35100 S. Rt. 53, Suite 79 Braceville, IL 60407 Illinois Emergency Management Agency Division of Disaster Assistance &
Preparedness 110 East Adams Street Springfield, IL 62701-1109 Chairman Will County Board of Supervisors Will County Board Courthouse Joliet, IL 60434 Braidwood Station Manager Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619
Byron/Braidwood Stations Ms. Bridget Little Rorem Appleseed Coordinator 117 N. Linden Street Essex, IL 60935 Document Control Desk-Licensing Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Exelon Generation Company, LLC Site Vice President - Braidwood 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Senior Vice President, Nuclear Services Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President Mid-West Operations Support Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Senior Vice President Mid-West Regional Operating Group Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Director Licensing Mid-West Regional Operating Group Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Exelon Generation Company, LLC Regulatory Assurance Supervisor -
Braidwood 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Exelon Generation Company, LLC Regulatory Assurance Supervisor - Byron 4450 N. German Church Road Byron, IL 61010-9794 Senior Counsel, Nuclear Mid-West Regional Operating Group Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Manager Licensing - Braidwood and Byron Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555